Self-sealing container for pressurized electro-conducting media

ABSTRACT

A self-sealing container for pressurized electro-conducting media including toroidal solid thin shells with flexible lip elements covered by a thin film of low friction plastic with electrical isolating and sealing features (for example Teflon type material). Each toroidal solid thin shell contacts with another shell by ball-socket type shape. Initial axial squeezing force during assembly creates the primary seal. Internal pressure from outside source or internal electrochemical reaction forces flexible lip elements against each other and creates contact force between each pair of ball-socket type shapes. The contact force is applied to the plastic film to seal internal volume of container.

BACKGROUND OF THE INVENTION

[0001] I. Field of the Invention

[0002] The present invention relates generally to high pressure storage, in particular to a self-sealing container for pressurized electro-conducting media adaptable for fuel cell and electorlyser applications.

[0003] II. Description of the Prior Art

[0004] Flexible metal hose is commonly used for conveying gases and simultaneously accommodates vibrations. In particular, the internal pressure tends to increase the sealing effect by pushing the sealing elements against other band elements.

[0005] Maximum internal pressure is determined only by friction force between two contacting bend elements. Additionally, absence of electrical isolator between contact elements makes it impossible to use flexible metal hose as container for pressurized electro-conducting media. (U.S. Pat. No. 6,378,561 B1)

[0006] Other applications related to electrochemical cell and electrochemical systems use one piece of unitary electrode. An insulating wall separates compartments of adjacent electrode pair assemblies which are connected by the double electrode plate in the single stack electrolyser. Each cell element contacts the next through an electrically isolating flat plastic gasket. The sealing effect is only achieved by preliminary squeezing load. The internal pressure initiated by electrochemical reaction expands the electrode-gasket sandwich and decreases pressure containing ability. Maximum internal pressure is determinate by preliminary squeezing loading and friction between electrode and gaskets. (U.S. Pat. No. 6,395,154 B1)

[0007] The present invention uses internal pressure from an electrochemical reaction to seal each electrochemical cell. Internal pressure helps seal the cells unlike traditional system, the coating of low friction plastic serves two functions: sealing and electro isolating.

[0008] The self-sealing container could be assembled at any length from identical elements. The value of internal pressure is determined by strength of materials of the toroidal solid thin shells and shapes of thin shells.

SUMMARY OF INVENTION

[0009] It is an object of the present invention to provide an electrochemical system which has self-sealing and electrical isolating feature between cells; the maximum internal pressure is determined by strength of material of the toroidal solid thin shells and shapes of thin shells.

OBJECTS AND ADVANTAGES OF THE INVENTIONS

[0010] The principal object and advantage of the present invention is to provide a self-sealing container of any length assembled from identical elements; providing element shape reduces wall thickness required to contain pressure due to flexible shape; providing a self-sealing container in which each elements are electrically isolated but mechanically connected; providing such self-sealing container which is leak resistance; providing self-sealing container which can be manufactured by standard stamping equipment or more economical way by bellow type forming machine; providing self-sealing container which is efficient in operation, capable of high number of pressurized/depressurized cycles and which is particularly very adapted for the purposes and application thereof.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 is across-sectional view of a prior self-sealing flexible metal hose.

[0012]FIG. 2 is perspective exploded view of a two cell single stack elctrolyser with flat gasket sealing internal volume between two electrodes.

[0013]FIG. 3 is a view of multiple thin shell stacks with applied axial primal squeezing force and internal pressure build by electrochemical reaction.

[0014]FIG. 4 is a view of one contact element with thin layer of coated plastic

[0015]FIG. 5 is view of the stress distribution in body of toroidal solid thin shells initiated by internal pressure

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention is related to the design of arrays of electrochemical cells (cell stacks) to keep internal pressure 1 (FIG. 3), initiated by electrochemical reaction. The value of the internal pressure 1 is a function of the shape and material properties of the toroidal solid thin shells. The preliminary loading by external force 3 provides the initial seal and allows the electrochemical reaction to start to increase pressure. The film of low friction plastic 4 (FIG. 4) on contact lip elements 5 and spherical ball type shape 6 not only provides sealing effect but simultaneously supports the electro isolation of electrochemical cells from each other.

[0017] Referring to the drawings in more detail FIG. 3, spherical shape 7 of the toroidal solid thin shells 2 provides a pattern for spreading stress into body of toroidal solid thin shells 2 initiated by internal pressure 1 which changes the shape 8 of thin shells 2 to the shape 9 close to spherical surface. In this case, the stress generated in the material of thin shells 2 converts from lateral type to longitudinal type. The stress limit will be very close to the yield limit of defined material.

[0018] Moreover, the change in shape 8 of thin shells 2 from conical types to more spherical types brings down equivalent stress.

[0019] Hence spherical shape 7 of the toroidal solid thin shells 2 are holds larger internal pressure in comparison to the traditional non spherical shape.

[0020] A reaction force 10 at the point of contact 11 between lip elements 5 and spherical ball type shape 6 (FIG. 4) is sum of force generate by internal pressure 1 and force initiated by changing shape of the toroidal solid thin shells 2.

[0021]FIG. 5 shows more detailed picture of equivalent stress (Von Mises) generated by internal pressure 1 and alteration of the shape toroidal solid thin shells 2. The darkest area represents more local stress.

[0022] An additional cathode shoulder 12 and membrane-anode shoulder 13 is destined for holding additional elements of electrolyser apparatus. 

What is claimed is: 1) a self-sealing container for pressurized electro-conducting media, which includes toroidal solid thin shells 2) said a flexible lips element belongs to thin shells 3) said thin film of low friction plastic that covered lips elements serves two functions: electro isolating and sealing 4) said toroidal solid thin shells contact with other shells by ball-socket type shape 5) said initial axial squeezing force created primal sealing 6) said internal pressure from outside source or internal electrochemical reaction bend flexible lips element against each other and creates contact force between each pair of spherical ball-socket shape. 7) said a contact force is applied to plastic film to seal internal volume of container 8) said a self-sealing container at any length can be assembled from identical elements. 